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Discussion Starter #21
I would be very cautious about striking at the hole access to the needle bearing as you probably cant hit the pinion shaft end but just the needle bearing race...you dont want to damage that. I would try hitting on the flat back shoulder of the driving gear teeth with something soft that wont damage teeth. The needle bearing is likely similar to that for the end of the ring gear shaft which you could see in earlier pics.
Thanks for all your help dmil123. Just wanted to tell you i got the bearing out. I had my buddy come over and take a look. he brought his heat gun over and put it right on the top of the housing for less then 30 seconds and the whole shaft pryed like it was nothing. I put the screwdriver against the flat surface of the gear like in the picture i showed and it popped right out. Now i just need to take it to the shop where we have a press. A guy on another forum said it also worked just using 2x4s but i have the press availabe. Next challenge I have is to make sure the distance between gears is right. Since the replacement bearing is a whole new part i have concerns about the gears linning up right. Have you ever heard of using some yellow goo (not sure what its called) in the gear that hardens for you to determine shim placement without having to do measurements?
 

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us the heat gun when you put the new bearing in too

or put the bearing in dry ice -100F
 

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Thanks for all your help dmil123. Just wanted to tell you i got the bearing out. I had my buddy come over and take a look. he brought his heat gun over and put it right on the top of the housing for less then 30 seconds and the whole shaft pryed like it was nothing. I put the screwdriver against the flat surface of the gear like in the picture i showed and it popped right out.....Have you ever heard of using some yellow goo (not sure what its called) in the gear that hardens for you to determine shim placement without having to do measurements?
That's great! Please post some pics of the failed bearing for other 650 owners to see. Check the pinion shaft and ring gear shaft needle bearings and make sure they turn smoothly as long as you have it apart. I know there is some sort of plastigauge that compresses to check spacing. I havent ever done this repair (yet) so maybe someone can jump in on the shim replacement. I just wonder if its the same housing, ring gear shaft and pinion shaft why checking shims is necessary. you are replacing an outboard bearing which is machined to very exacting tolerances and sits against shoulders on the pinion shaft and pressed into a shoulder in the housing. What would change the spacing. My advice is to read that section of the shop manual very carefully. post a pic of the new bearing as well. I am curious to know how it was improved.
 

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just another thought to add.. make sure you replace ALL orings and seals. It would be a shame to get it back together and have it leak oil.
 

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Discussion Starter #26
That's great! Please post some pics of the failed bearing for other 650 owners to see. Check the pinion shaft and ring gear shaft needle bearings and make sure they turn smoothly as long as you have it apart. I know there is some sort of plastigauge that compresses to check spacing. I havent ever done this repair (yet) so maybe someone can jump in on the shim replacement. I just wonder if its the same housing, ring gear shaft and pinion shaft why checking shims is necessary. you are replacing an outboard bearing which is machined to very exacting tolerances and sits against shoulders on the pinion shaft and pressed into a shoulder in the housing. What would change the spacing. My advice is to read that section of the shop manual very carefully. post a pic of the new bearing as well. I am curious to know how it was improved.
So i finally got all of the parts in to do the final drive bearing replacement. Just so you can see what I did. I removed the gear oil casing after draining it tonget access to the gear. Them after removing the reverse thread retainer I heated the housing up with a heat gun right where the bearing sits and pryed the gear out using a screwdriver (pic 1). Once heated it slid out easily. You can see in pic 2 what the assembly looks like removed. Then i used a press to take the bearing and spacer off at the same time (pic 5). Pic 3 and 4 is of the new bearing that I pressed on. I then reheated the housing and slightly tapped the new bearing and pinnion gear in place. Then reinstalled reverse thread bearing making sure to put the new o-ring on the retainer and on the housing. Pretty easy job if you have a heat gun, and a press. I also did the measurement using a micrometer to measure the near the bearing and they were relatively the same.
 

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thanks for sharing details of the repair. The disintegrated retainer for the bearing balls in image 5 looks positively scary. If a piece of that were to get in the final drive gear mesh while riding, it could cause the rear wheel to immediately seize, causing a bad crash! I learned a few things from your postings for when I get around to the repair. I'm surprised there has never been a safety recall and now I am curious as to what year Yamaha implemented the upgrade. By any chance, do you have a close-up of the new bearing before install... just curious as to how they changed it. Should be something to consider for all 650 owners who have the original style bearing. Happy trails... ride safe and stick around on the forum. Glad to have you.
 

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Discussion Starter #28
thanks for sharing details of the repair. The disintegrated retainer for the bearing balls in image 5 looks positively scary. If a piece of that were to get in the final drive gear mesh while riding, it could cause the rear wheel to immediately seize, causing a bad crash! I learned a few things from your postings for when I get around to the repair. I'm surprised there has never been a safety recall and now I am curious as to what year Yamaha implemented the upgrade. By any chance, do you have a close-up of the new bearing before install... just curious as to how they changed it. Should be something to consider for all 650 owners who have the original style bearing. Happy trails... ride safe and stick around on the forum. Glad to have you.
I didnt take a pic but googled the part number and the screen shot is what it looks like. I was suprised to see though that the bearing is not enclosed. The center metal retainer also comes out on both sides to expose the balls. As for the ride, after a carb rebuild and doing this project she runs like a champ. I think I have a new issue though and will be posting on the a new thread to see if anyone has any inputs.
 

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